In a service oriented architecture (SOA), disparate applications use distributed services to retrieve/persist data in a standardized manner. These distributed services are independent from particular applications and are accessible by the applications requesting the service (e.g., via service requests). A service is a self-contained unit of functionality, such as retrieving an online bank statement. An application, or application program, is a software program that runs on a computer.
Services are combined by other software applications to provide the functionality of a large software application. SOA facilitates cooperation among computers connected over a network. A computer runs an arbitrary number of services, and each service is built in a way that ensures that the service can exchange information with others service in the network, without human interaction and without the need to make changes to the underlying program itself.